A correction is defined as a 10 percent decline in major averages from their highs. As of Tuesday's close, the Dow Jones Industrial Average was down 2 percent, the S&P 500 was down 1.5 percent, while the Nasdaq was off 6 percent from their 52-week highs.

"There's more selling to come. There's judicious selling to come," he added, but warned investors that it's next to impossible to pick the bottom. "If you did, you just got bloody lucky. But there will be times when you get panic selloffs that my propensity then will be say, 'I shall begin to buy some.' If it works I'll buy more."

"With each passing day, we are more and more fearful too that a correction of some very real magnitude is hard upon us as the broader market indices such as the Russell and the NASDAQ have now 'failed' well below their previous highs and as upward sloping trend lines cast back into last year have been broken through to the downside."

In a CNBC interview Monday, he also said he thought stocks were still in a bull market.

There's no doubt that this market is baffling many experts, but all these mixed signals may be leaving some investors wondering if Gartman is crying wolf.

In February, he walked back an earlier prediction that stocks could see at 15 percent correction. "Vociferously, I'd say I was wrong," he had said at the time, as stocks hit new highs.

But looking at individual names, the head of O'Shaughnessy Asset Management warned investors to stay away from the most traded stocks. "Generally speaking, you want to avoid them like the plague. They end up turning in horrible results over the last 45 years."